1. Field of the Invention
The present invention relates to an ink cartridge that stores ink to be supplied to an ink-jet head, and also relates to an ink-jet recording apparatus using the ink cartridge.
2. Description of Related Art
In an ink-jet recording apparatus such as ink-jet is printers, in order to record a good image on a recording medium, it is important that proper meniscus is formed at each nozzle of an ink-jet head. For keeping meniscus of nozzles in a proper condition, pressure applied to the nozzles should be kept within a predetermined range.
When positive pressure or excessively small negative pressure is applied to nozzles, meniscus is broken to cause such a disadvantage as ink dripping from the nozzles. Besides, when excessive negative pressure is applied to nozzles, air bubbles can enter the nozzles to disadvantageously cause ink ejection disability, unstable ejection, and the like. Therefore, pressure to be applied to nozzles has to fall within a predetermined negative range.
Thus, known is a technique of producing negative pressure in nozzles by means of a difference in level between an ink-jet head including nozzles and a cartridge for storing liquid that will be supplied to the head (see U.S. Patent Application Publication No. 2002122084). According to this technique, a cartridge is mounted in a horizontal manner. An upper face of a liquid bag included in the cartridge is fixed to a housing, while a lower face of the liquid bag is freely movable depending on a change in the amount of liquid therein, so that the lower face moves upward when the amount of liquid decreases. As a result, even when the amount of liquid in the liquid bag is changed, pressure applied to nozzles does not vary so much and can be kept within a predetermined range.